This invention relates to tablet type switching devices, and particularly to stop tablet mechanisms for use in electric organs wherein a number of stop tablets are arranged in side-by-side relation for convenient actuation by the organist.
Stop tablet mechanisms are known wherein springs of various types are utilized to suspend or cradle the tablets for movement to their alternate positions of use, usually from a normal "up" position to an operated "down" position. A form of spring in common use is one that provides an over center snap as the tablet is displaced from either of the two positions, and the ultimate "up" and "down" positions of the tablet are determined by engagement of the tablet with the upper and lower edges, respectively, of a narrow slot in the organ console through which the tablets project. In mechanisms of this type, displacement of the activated tablets from their normal rest position provides an indication to the organist of which stops are on. An objection to such mechanisms is that the felt with which the edges of the slot is usually lined to reduce noise caused by the snap action of the tablets is subject to uneven wear and/or compression as between frequently used and little used tablets, with the result their positions in the normal and operated positions may vary from tablet to tablet and detract from the appearance of the organ.
In an application filed concurrently herewith by Richard H. Peterson and Richard W. Jensen entitled, "Indicating Organ Stop Tablet", Ser. No. 810,136 there is described a stop tablet control system in which the "on" condition of selected stops is indicated by an illuminated light emitting diode mounted in each stop tablet, the energization of which is controlled by latching circuit means operative in response to momentary depression of a stop tablet from a neutral position. When the tablet is momentarily pushed up from the neutral position, the associated stop is turned "off" and the light emitting diode is extinguished. Thus, instead of employing springs of the type that have long been used in organ stop tablet mechanisms which provide an over center "snap" as the tablet is displaced from its normal position to the operated position, the tablets are spring-biased to assume a neutral position from which they can be momentarily moved up or down against the action of the spring.
It is a primary object of the present invention to provide a stop tablet mechanism that is easy to manufacture and adjust, which maintains the tablets in a preset neutral position with relative firmness, and wherein the tablets can be momentarily moved up or down against the action of a spring and returned to the pre-set neutral position.